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Date of release: 24 August, 2009

Type of exercise and bone protection


The cumulative risk of fracture for a postmenopausal woman over the age of 50 years can reach up to 60%. Exercise has the potential to modify fracture risk in postmenopausal women through its effects on bone mass and geometry [1]. To determine the magnitude of these effects in postmenopausal women, Hamilton and colleagues have performed a systematic literature review looking for studies which used peripheral quantitative computed tomography (p-QCT) as the method of assessment [2]. The QCT-based techniques correlate well with the geometry, biomechanics and strength of bones and may predict fracture risk. Of 293 publications screened, only 12 were included in the final analysis (four randomized, controlled trials, one non-randomized trial, three cross-sectional studies and four prospective cohort studies). Their main finding was that exercise appeared to positively influence bone mass and bone geometry in postmenopausal women; however, exercise effects seemed to be modest, site-specific and preferentially influence cortical rather than trabecular components of bone. Exercise type also played a role, with the most prominent mass and geometric changes being observed in response to high-impact loading exercise.

Comment

Clinicians are often faced with a dilemma as to which exercise program should be advised to menopausal women and what is the true efficacy of this measure. Cross-sectional studies show in general that exercise modalities requiring high forces and/or generating high impacts have the greatest osteoprotective potential [3]. It is not clear which training method is superior for bone stimulation in adults, although scientific evidence points to a combination of high-impact (i.e. jumping) and weight-lifting exercises. In addition, exercise targeted at improving balance, mobility and posture should be recommended to reduce the likelihood of falling and its associated morbidity and mortality. In this comprehensive review, more than 290 studies were evaluated but no more than 12 studies were found to be appropriate for evaluation. An exercise program should be adapted to the age of the patient; however, eight of the 12 studies assessed postmenopausal women between the ages of 50 and 71 years, one study enrolled patients under the age of 50 years and three studies examined a more elderly population (women over the age of 72 years). This inconsistency makes result interpretation complex. Importantly, this review highlighted that a variety of exercise types can be beneficial for bone geometry and the type of exercise seems to play a role in influencing the degree of the training effect. According to this review, the physician should recommend menopausal women to perform physical activity which involves high-impact, rapid, forceful loading (running, jumping) or either changing, diverse, or novel loading angles (ball sports) and weight-bearing, high forces (dancing, weight lifting) and a direct impact on the bone of interest (tennis game). Nevertheless, the exercise programs and studied samples in the enrolled studies varied in frequency, duration, training period and type of exercise; thus, there is a need for a large, well-controlled, prospective, randomized trial.

Comentario

Bari Kaplan
Beilinson Womens Hospital, Rabin Medical Center and Tel Aviv University Faculty of Medicine, Israel

    References

  1. Feskanich D, Willett W, Colditz G. Walking and leisure-time activity and risk of hip fracture in postmenopausal women. JAMA 2002;288:2300-6.
    http://www.ncbi.nlm.nih.gov/pubmed/12425707

  2. Hamilton CJ, Swan VJ, Jamal SA. The effects of exercise and physical activity participation on bone mass and geometry in postmenopausal women: a systematic review of pQCT studies. Osteoporos Int 2009 Jun 6 [Epub ahead of print].
    http://www.ncbi.nlm.nih.gov/pubmed/19504035

  3. Guadalupe-Grau A, Fuentes T, Guerra B, Calbet JA. Exercise and bone mass in adults. Sports Med 2009;39:439-68.
    http://www.ncbi.nlm.nih.gov/pubmed/19453205